'Previously booted entry' option not working in Ubuntu 16.04

It works well for me…

Paste your /boot/grub/grub.cfg please.

Here it is:

#
# DO NOT EDIT THIS FILE
#
# It is automatically generated by grub-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub
#

### BEGIN /etc/grub.d/00_header ###
if [ -s $prefix/grubenv ]; then
  set have_grubenv=true
  load_env
fi
if [ "${next_entry}" ] ; then
   set default="${next_entry}"
   set next_entry=
   save_env next_entry
   set boot_once=true
else
   set default="${saved_entry}"
fi

if [ x"${feature_menuentry_id}" = xy ]; then
  menuentry_id_option="--id"
else
  menuentry_id_option=""
fi

export menuentry_id_option

if [ "${prev_saved_entry}" ]; then
  set saved_entry="${prev_saved_entry}"
  save_env saved_entry
  set prev_saved_entry=
  save_env prev_saved_entry
  set boot_once=true
fi

function savedefault {
  if [ -z "${boot_once}" ]; then
    saved_entry="${chosen}"
    save_env saved_entry
  fi
}
function recordfail {
  set recordfail=1
  if [ -n "${have_grubenv}" ]; then if [ -z "${boot_once}" ]; then save_env recordfail; fi; fi
}
function load_video {
  if [ x$feature_all_video_module = xy ]; then
    insmod all_video
  else
    insmod efi_gop
    insmod efi_uga
    insmod ieee1275_fb
    insmod vbe
    insmod vga
    insmod video_bochs
    insmod video_cirrus
  fi
}

if [ x$feature_default_font_path = xy ] ; then
   font=unicode
else
insmod part_msdos
insmod ext2
set root='hd0,msdos9'
if [ x$feature_platform_search_hint = xy ]; then
  search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos9 --hint-efi=hd0,msdos9 --hint-baremetal=ahci0,msdos9 307a06b6-1861-4091-82c0-36909d647c8f
else
  search --no-floppy --fs-uuid --set=root 307a06b6-1861-4091-82c0-36909d647c8f
fi
    font="/usr/share/grub/unicode.pf2"
fi

if loadfont $font ; then
  set gfxmode=auto
  load_video
  insmod gfxterm
  set locale_dir=$prefix/locale
  set lang=en_IN
  insmod gettext
fi
terminal_output gfxterm
if [ "${recordfail}" = 1 ] ; then
  set timeout=30
else
  if [ x$feature_timeout_style = xy ] ; then
    set timeout_style=menu
    set timeout=10
  # Fallback normal timeout code in case the timeout_style feature is
  # unavailable.
  else
    set timeout=10
  fi
fi
### END /etc/grub.d/00_header ###

### BEGIN /etc/grub.d/05_debian_theme ###
insmod part_msdos
insmod ext2
set root='hd0,msdos8'
if [ x$feature_platform_search_hint = xy ]; then
  search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos8 --hint-efi=hd0,msdos8 --hint-baremetal=ahci0,msdos8 b54cdeb3-d0f8-46be-a5c7-fab881752428
else
  search --no-floppy --fs-uuid --set=root b54cdeb3-d0f8-46be-a5c7-fab881752428
fi
insmod jpeg
if background_image /ashish/Pictures/Wallpapers/hp-spider-wall-wallpapers1024x768.jpg; then
  set color_normal=light-blue/black
  set color_highlight=white/black
else
  set menu_color_normal=white/black
  set menu_color_highlight=black/light-gray
  if background_color 44,0,30,0; then
    clear
  fi
fi
### END /etc/grub.d/05_debian_theme ###

### BEGIN /etc/grub.d/10_linux ###
function gfxmode {
 set gfxpayload="${1}"
 if [ "${1}" = "keep" ]; then
  set vt_handoff=vt.handoff=7
 else
  set vt_handoff=
 fi
}
if [ "${recordfail}" != 1 ]; then
  if [ -e ${prefix}/gfxblacklist.txt ]; then
    if hwmatch ${prefix}/gfxblacklist.txt 3; ...

Your windows 10 menuentry, which is manually modified, has no "savedefault" call. Just add the line "savedefault" at the top of this menuentry.

Thanks a lot for the suggestion. It works all right now.

However, I did not modify Windows 10 menuentry manually being not knowledgeable in this. I did, however, change the name of the menuentry via grub-customizer and no more. Why was 'savedefault' not added by grub-customizer on choosing the option of 'previously booted entry' should still be assessed I suppose.

Now my menuentry (after manual modification), looks as under and works perfectly.

menuentry "Windows 10" --class windows --class os $menuentry_id_option 'osprober-chain-26F20FADF20F8073' {
 savedefault
 insmod part_msdos
 insmod ntfs
 set root='hd0,msdos1'
        ...
        ...

I assume the same problem bugs my other laptop which has Ubuntu 16.04 and Win7. I shall make changes in grub.cfg there also. Thanks a lot for your help.

I'm facing the same exact issue on 16.04 for both: Windows and Ubuntu entries. I've edited the names as Ashish did.

Manually adding savedafeault helped.

Still a problem in 17.10.